The Brooks family of extremely high-performing direct liquid injection (DLI) vaporizer solutions is designed for customers who require reliable liquid vaporization. Featuring unique atomization and heat exchanger technologies, Brooks direct liquid injection vaporizers deliver pure vapor for every application. Applications include:
- Water vaporization for fuel cell stack humidification and many other water addition applications
- Liquid precursor vaporization for chemical vapor deposition (CVD), metal oxide chemical vapor deposition (MOCVD), and atomic layer deposition (ALD)
- Depositing thin films for enhanced thermal, optical, or hardness characteristics such as diamond-like carbon coating and glass coating
- Vaporizing monomers for vacuum polymer film deposition
- Generating calibration vapor
- Vaporizing liquid hydrocarbons
- Many more
Brooks' direct liquid injection vaporizer technology overcomes the many limitations of conventional vaporizing technologies. Bubblers, or vapor draw systems, are difficult to start and stop, require very close control of temperature and pressure, and are inefficient at generating well controlled vapor mass flow. Vaporizing valves, hot frit, heat tracing, and other "flash vaporizers" that apply heat to the liquid using a hot metal surface are also inefficient at generating vapor mass and frequently can cause thermal decomposition of the liquid precursor. None of these conventional technologies can eliminate the potential for liquid carry-over and its attendant problems. Figure 1 on page 2 illustrates CVD deposition chamber pressure fluctuations caused by incomplete vaporization and precursor carry-over from a conventional vaporizer.
Furthermore, it is very challenging to determine precisely how much vapor mass is actually being delivered from a conventional vaporizer. In applications that require precise vapor mass addition, users must turn to secondary measurement/control devices such as vapor mass flow controllers, increasing the cost and complexity of the vapor module.
Direct Liquid Injection Vaporizer
A Brooks direct liquid injection vaporizer employs hot gas, rather than a hot metal surface, to accomplish liquid vaporization. As liquid enters the hot gas chamber, it is atomized by a carrier gas stream. Once the atomized liquid contacts the hot gas, it immediately changes to vapor. The result is chemically pure vapor, free of decomposition byproducts or liquid carry-over. Moreover, a Brooks direct liquid injection vaporizer can accept multiple liquid inlets and will generate perfectly mixed vapors. Brooks offers several heat exchanger designs to accommodate an extraordinarily wide range of liquid properties: extremely low vapor pressures (sub 1 torr), very low flow rates (sub 5 grams per hour), and very high flow rates (more than 15 kg/hr). Unlike bubblers and hotsurface vaporizers, Brooks direct liquid injection vaporizers are extremely efficient at producing vapor from liquid.
The Brooks direct liquid injection vaporizer is close to being a true "vapor-on-demand" system because increasing, decreasing, or stopping the incompressible liquid flow quickly results in the desired change in vapor flow. Figure 2 demonstrates the Brooks direct liquid injection vaporizer’s extremely fast response to 900 g/hr tetraethyl orthosilicate (TEOS) step challenges. By comparison, for example, the large bubblers commonly used for MTS (methyltrichlorosilane), BCl3, TiCl4 and similar liquids are difficult to start, run, and stop effectively.
Direct Liquid Injection Vaporizer
- Allowable process pressure: vacuum to many atmospheres
- Vapor capacity: less than 5 grams per hour to greater than 15 kg per hour. (In calibration vapor applications, the target analyte concentrations may be achieved proportioning the liquid and carrier gas flows.)
- Accepts multiple liquid feeds
- Sample wetted materials: 316L stainless steel with elastomer seals; all welded 316L; or electropolished 316L with nickel seals
- Vaporizer chamber heating: electric band heater
- Heater power: less than 100W to greater than 5000W, application dependent; 100, 115, or 230 VAC
- Temperature sensors: 2 K-type thermocouples, 1 for chamber temperature and 1 for over-temperature alarm
- Process connections: 1/8" to 1" compression, face-seal, or NPT typical
- Leak integrity: 1 X 10-9 cc/sec helium
- Dimensions: vary by application. A 400W DLI vaporizer is approximately (HWD) 7.5" x 5" x 5" (200mm x 125mm x 125mm)
Liquid Flow Controller
Brooks' Quantim Coriolis liquid flow controller is recommended in most applications. Unlike conventional thermal liquid flow controllers, the Quantim is insensitive to liquid properties. Quantim also measures liquid density which can provide important diagnostic confirmation about the liquid being controlled.Gas Flow Controller
A Brooks thermal mass flow controller is recommended in most applications. Brooks offers a variety of digital, analog, elastomer sealed, and all-metal UHP designs depending on the application requirements.